Reconstruction of a mandibular critical-sized defect using iliac graft in rats.

Objective: To evaluate, histologically and by optical densitometry of radiographs, the healing of a critical-sized defect in the rat mandible filled with iliac graft.

Materials: The study was conducted on 25 adult Wistar rats. With the rats under general anesthesia, a bicortical critical-sized osseous defect was created in the right mandibular ramus and filled with autogenous iliac crest graft. The animals were divided into 5 groups, with 5 rats in each. They were sacrificed after 1, 7, and 14 days, and 1 and 3 months. The mandibles were removed, fixed in formalin, and radiographed. The right hemi-mandibles were decalcified, and sections were cut and stained with hematoxylin and eosin.

Results: Initially, an acute inflammatory process was noted along the graft that was tightly fitted to the defect. Subsequently, intense bone neoformation from external corticals and in the inner spaces of the graft was observed, while medullar spaces were occupied by granulation tissue and osteoblasts. There was remodelation of the receptor site, with a decrease in the graft volume and medullary space, as well as cancellous bone replaced by compact bone. Later, the receptor site was similar to the normal mandible, and only devitalized remnants of corticals of the graft were found. Optical densitometry of radiographs revealed statistically significant differences between experimental and control sites.

Conclusions: This experimental model is valuable in the study of bone healing. The study showed that autogenous iliac graft promoted healing of the critical-sized defect of the mandible with complete bony remodeling.